This film doesn't appear to have been copyrighted, so it's difficult to say when it was made, outside of the talk of ten years of TV experimentation by RCA. There's no reference to the war so it may be from 1940 at the latest.
Supervisor Frank Donovan was a producer-director of RKO shorts in the 1940s, while Frederic Ullman, Jr. was president of Pathe News until 1944 when he became president of RKO Television Corp.
The reel starts with a 60 second ad for RCA's sound system for theatres then launches into a short film from a time that W2XBS (WNBT in July 1941) wasn't airing a lot of television. The voiceover is by Andre Baruch.
It's odd there are no call letters on the NBC-RCA cameras.
The Clem McCarthy race call is intriguing. Sun Crax, Albert D, Interpreter and Judge Hasten ran together in NYC on March 31, 1939. Some of the footage was used in Burton Holmes' 1940 short "Radio and Television."
There's an excellent look at early TV directing as a concert is underway.

First a brief promtional of RCA sound projectors is seen. The narrator sounds like Milton Cross, famous radio commentator of music. The rest of the film is now of historic interest. It shows the mechanics of television pre W.W.II. (During the war, the station went off the air.) By 1947, the television tube did not show reverse images and the slanted mirror was no longer needed.

An interesting film which tells of the wonders of televsion, whether it be a live broadcast of a horse race, or a concert, we see the (then) complex ways of how the broadcast is all put together, and even how a television (read, kinescope) is put together.. Get a load of those giant television tubes!